Conventional laser receivers detect incoming laser light beams by use of one or more laser light sensors that are impacted by the laser light beam. The laser light sensor(s) typically output one or more electrical signals that are directed to a control circuit that determines the position where the laser light beam has impacted on the sensor(s). If the laser light beam strikes the sensor(s) at a specific predetermined location (or within a small range of such locations), then the laser receiver is then said to be “on-grade,” which often is the desired location at that moment. If the laser light beam strikes the sensors(s) at a different location, then the laser receiver is then said to be either “above-grade” or “below-grade.” These grade indications are typically displayed on some type of easily viewed LCD or LED display built into the laser receiver, and the user will then know which way to move the laser receiver to ultimately position it in the ON-grade position. Once properly located, the laser receiver in essence “tells” the user that he or she can begin work on that portion of the construction site.
Other ways of using a laser receiver also can be useful. For example, an “offset” on-grade mode of a laser receiver typically provides more sensing height when the user is working above the “on-grade” position of the sensor than below “on-grade.” In other words, the laser light sensors extend for a greater distance below the on-grade position (on the laser receiver's sensors) than above the on-grade position. This is useful in situations where a worker is removing material from a jobsite (when using a bulldozer, for example), thereby allowing gradual removal of material until an on-grade condition is achieved, thus reducing the chances of overshooting the target elevation, where material would then have to be added to correct for this. It is also useful in gradually driving reference stakes to the correct elevation on a jobsite, again reducing the chances of overshooting the target elevation where a stake would then have to be adjusted by pulling it up out of the ground.
The use of an “offset” on-grade mode could also provide more sensing height below grade than above grade, and if this adjustment is desired by a user/customer, it could be made available as an option. This is not commonly desired by most users/customers, but it could be useful in a situation where material is being added to a jobsite.